I'm please to report that after finding an old 500gb SSD behind the sofa and migrating a bunch of other games to it, Orbx Central took about 20 minutes to convert the files and I've already flown over my house several times
Also I can now see the 3rd piece of the Great Britain puzzle (The North) is now being offered to me for discount price!
Never would have thought a 27gb download would need 300+ gigs of space to do it's thing, but you guys apparently pack those install files denser than a black hole, so...
Appreciate the help!